5 research outputs found
Roll-to-Roll Transfer of Electrospun Nanofiber Film for High-Efficiency Transparent Air Filter
Particulate matter (PM) pollution
in air has become a serious environmental
issue calling for new type of filter technologies. Recently, we have
demonstrated a highly efficient air filter by direct electrospinning
of polymer fibers onto supporting mesh although its throughput is
limited. Here, we demonstrate a high throughput method based on fast
transfer of electrospun nanofiber film from roughed metal foil to
a receiving mesh substrate. Compared with the direct electrospinning
method, the transfer method is 10 times faster and has better filtration
performance at the same transmittance, owing to the uniformity of
transferred nanofiber film (>99.97% removal of PM<sub>2.5</sub> at
ā¼73% of transmittance). With these advantages, large area freestanding
nanofiber film and roll-to-roll production of air filter are demonstrated
Thermal Management in Nanofiber-Based Face Mask
Face
masks are widely used to filter airborne pollutants, especially
when particulate matter (PM) pollution has become a serious concern
to public health. Here, the concept of thermal management is introduced
into face masks for the first time to enhance the thermal comfort
of the user. A system of nanofiber on nanoporous polyethylene (fiber/nanoPE)
is developed where the nanofibers with strong PM adhesion ensure high
PM capture efficiency (99.6% for PM<sub>2.5</sub>) with low pressure
drop and the nanoPE substrate with high-infrared (IR) transparency
(92.1%, weighted based on human body radiation) results in effective
radiative cooling. We further demonstrate that by coating nanoPE with
a layer of Ag, the fiber/Ag/nanoPE mask shows a high IR reflectance
(87.0%) and can be used for warming purposes. These multifunctional
face mask designs can be explored for both outdoor and indoor applications
to protect people from PM pollutants and simultaneously achieve personal
thermal comfort
CoreāShell Nanofibrous Materials with High Particulate Matter Removal Efficiencies and Thermally Triggered Flame Retardant Properties
Dust filtration is
a crucial process for industrial waste gas treatment.
Great efforts have been devoted to improve the performance of dust
filtration filters both in industrial and fundamental research. Conventional
air-filtering materials are limited by three key issues: (1) Low filtration
efficiency, especially for particulate matter (PM) below 1 Ī¼m;
(2) large air pressure drops across the filter, which require a high
energy input to overcome; and (3) safety hazards such as dust explosions
and fires. Here, we have developed a āsmartā multifunctional
material which can capture PM with high efficiency and an extremely
low pressure drop, while possessing a flame retardant design. This
multifunctionality is achieved through a coreāshell nanofiber
design with the polar polymer Nylon-6 as the shell and the flame retardant
triphenyl phosphate (TPP) as the core. At 80% optical transmittance,
the multifunctional materials showed capture efficiency of 99.00%
for PM<sub>2.5</sub> and >99.50% for PM<sub>10ā2.5</sub>, with
a pressure drop of only 0.25 kPa (0.2% of atmospheric pressure) at
a flow rate of 0.5 m s<sup>ā1</sup>. Moreover, during direct
ignition tests, the multifunctional materials showed extraordinary
flame retardation; the self-extinguishing time of the filtrate-contaminated
filter is nearly instantaneous (0 s/g) compared to 150 s/g for unmodified
Nylon-6
CoreāShell Nanofibrous Materials with High Particulate Matter Removal Efficiencies and Thermally Triggered Flame Retardant Properties
Dust filtration is
a crucial process for industrial waste gas treatment.
Great efforts have been devoted to improve the performance of dust
filtration filters both in industrial and fundamental research. Conventional
air-filtering materials are limited by three key issues: (1) Low filtration
efficiency, especially for particulate matter (PM) below 1 Ī¼m;
(2) large air pressure drops across the filter, which require a high
energy input to overcome; and (3) safety hazards such as dust explosions
and fires. Here, we have developed a āsmartā multifunctional
material which can capture PM with high efficiency and an extremely
low pressure drop, while possessing a flame retardant design. This
multifunctionality is achieved through a coreāshell nanofiber
design with the polar polymer Nylon-6 as the shell and the flame retardant
triphenyl phosphate (TPP) as the core. At 80% optical transmittance,
the multifunctional materials showed capture efficiency of 99.00%
for PM<sub>2.5</sub> and >99.50% for PM<sub>10ā2.5</sub>, with
a pressure drop of only 0.25 kPa (0.2% of atmospheric pressure) at
a flow rate of 0.5 m s<sup>ā1</sup>. Moreover, during direct
ignition tests, the multifunctional materials showed extraordinary
flame retardation; the self-extinguishing time of the filtrate-contaminated
filter is nearly instantaneous (0 s/g) compared to 150 s/g for unmodified
Nylon-6
In Situ Investigation on the Nanoscale Capture and Evolution of Aerosols on Nanofibers
Aerosol-induced
haze problem has become a serious environmental concern. Filtration
is widely applied to remove aerosols from gas streams. Despite classical
filtration theories, the nanoscale capture and evolution of aerosols
is not yet clearly understood. Here we report an in situ investigation
on the nanoscale capture and evolution of aerosols on polyimide nanofibers.
We discovered different capture and evolution behaviors among three
types of aerosols: wetting liquid droplets, nonwetting liquid droplets,
and solid particles. The wetting droplets had small contact angles
and could move, coalesce, and form axisymmetric conformations on polyimide
nanofibers. In contrast, the nonwetting droplets had a large contact
angle on polyimide nanofibers and formed nonaxisymmetric conformations.
Different from the liquid droplets, the solid particles could not
move along the nanofibers and formed dendritic structures. This study
provides an important insight for obtaining a deep understanding of
the nanoscale capture and evolution of aerosols and benefits future
design and development of advanced filters